• KCI Concrete Journal
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• v.11 no.3
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• pp.175-180
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• 1999

In order to predict the onset of the corrosion of steel bars in concrete, a mathematical model was presented to observe the diffusion of chloride ion in aqueous phase, the adsorption and desorption of chloride ions to and from the surface of solid phase of concrete, and the chemical reaction or chloride ions with solid phase. The finite element method was employed to carry out the numerical analysis. The chlorides enetrating through the wall of the concrete structure from the external environment and the chlorides contained in the concrete admixture were confirmed to be two important factors to determine the onset of the corrosion of steel bars.

• Journal of the Korean Applied Science and Technology
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• v.4 no.1
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• pp.53-59
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• 1987

Inosamine(deoxyaminoinositol) stereomers such as scyllo-inosamine, myo-inosamine-2, epi-inosamine-2 and myo-inesamine-4 have been synthesize from myo-inositol (1,2,3,5/4,6-hexahydroxycyclohexane) And sixteen of quaternary ammonium salt type deoxyaminoinositols such as dimethylalktl-deoxy-scyllo-inosityl-, dimethylalkyl-2deoxy-2myo-inosityl-, dimethylalkyl-2-deoxy-2-epi-inosityl and dimethylal inosityl-, dimethylalkyl-2-deoxy-2-myo-inosityl-, dimethylalkyl-2-deoxy-2-epi-inosityl and dimethylalkyl-4-deoxy-4-myo-imosityl ammonium chlorides with straight chain alkyl group having from eight to fourteen carton atoms have been synthesized from four kinds of the imosamine stereomers. The isolation and detection of dimethylalkyl-deoxy-inosityl ammonium chlorides have been investigated by column chromatography, paper chromatography, infrared absorption spectra and elementary analysis, respectively.

• Bulletin of the Korean Chemical Society
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• v.1 no.2
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• pp.57-62
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• 1980

Semi-empirical MO calculations were performed to investigate stereochemical properties of sulfamoyl chlorides; $R_2NSO_2Cl$ Where R = H or $CH_3$. It was found that for all the molecules considered the most preferred conformation was the form in which $n_N-{\sigma}^*_{SIC}$ conjugative interaction is a maximum and the least favored conformation was the form in which steric repulsion is large due to eclipsing of Cl and R. In case of the molecule with no symmetry i.e., $CH_2NHSO_2Cl$, the stability was also dependent upon nonbonded interactions between the eclipsing groups.

• Bulletin of the Korean Chemical Society
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• v.11 no.1
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• pp.60-64
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• 1990

The reactions of alkanesulfonyl chlorides with pyridines in the presence of various solvents have been studied by means of kinetic method. Alkanesulfonyl chlorides bearing ${\alpha}$-hydrogen with the normal attack of pyridine is found to be at the ${\alpha}$-hydrogen with elimination to form the sulfene intermediate evidently. From the mass spectra by the reaction of ethanesulfonyl chloride with 3-picoline in the presence of methanol-$d_1$, it has shown that the reaction has a witness favorable to the slulfene intermediate.

• Bulletin of the Korean Chemical Society
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• v.17 no.8
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• pp.712-715
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• 1996

Kinetic studies are carried out on the reactions of N-methyl-N-phenylcarbamoyl chlorides with benzylamines in acetonitrile. The selectivity parameters, ρX (=-0.6~-0.8), ρY (=1.0-1.1), and ρXY (=-0.14), suggest that the reaction proceeds by an SN2 mechanism. Kinetic isotope effects, kH/kD, involving deuterated nucleophiles (XC6H4CH2ND2) are all inverse type (<1.0), and the trends of changes in the magnitude are consistent with those expected for the observed negative sign of ρXY(=∂ρX/∂σY = ∂ρY/∂σX < 0). The relatively low activation enthalpies also support the proposed mechanism.

• Bulletin of the Korean Chemical Society
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• v.9 no.6
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• pp.376-378
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• 1988

Results of kinetic studies on the reactions of benzyl chlorides with anilines and benzylamines are reported. Analyses of the cross interaction constants relevant to the degree of bond formation, ${\rho}_{XY}$ and ${\lambda}_{XY}$, are carried out. The magnitudes of the two parameters indicated that the degree of bond formation in the transition state is the typical of that expected for an $S_N2$ reaction, but the reactions with benzylamines appear to have a slightly less degree of bond formation compared with the reactions with anilines.

• Bulletin of the Korean Chemical Society
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• v.15 no.7
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• pp.576-581
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• 1994

The secondary deuterium kinetic isotope effects (SDKIE) involving deuterated aniline nucleophiles are reported for the reactions of benzyl bromides and chlorides and benzoyl chlorides in acetonitrile. The benzyl systems behave normally as to the trend of changes in SDKIE with the magnitude of ${\rho}X({\rho}_{nuc})$, whereas benzoyl system shows ananomaly; ${\mid}{\rho}_X{\mid}$ decreases with increase in the extent of bond making estimated by the SDKIE. This has been ascribed to the negative charge accumulation at the reaction center carbon in the transition state. The magnitude of ${\rho}_{XY}$ is found to decrease by ca. 0.03 with ten degree rise in the reaction temperature.

• Bulletin of the Korean Chemical Society
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• v.19 no.6
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• pp.642-645
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• 1998

The aminolysis reactions of phenylacetyl chlorides with anilines and N,N-dimethylanilines (DMAS) in acetonitrile at -15.0 ℃ are investigated. The magnitude of ρx (= -2.8 ∼ -2.9) and ρy (= 0.9 ∼ 1.3, after correcting for the fall-off), and the negative sign of ρxy (= -0.12) for the reactions with anilines suggest an associative SN2 mechanism. For the reactions with DMAs, the magnitude of these Hammett coefficients increases so that tighter bond making in the transition state (TS) is predicted. A nonlinear Hammett plots obtained for the DMAs with an electron acceptor substituent is interpreted to result from a more advanced degree of leaving group departure to assist closer approach of the bulky DMA in the TS. The normal secondary kinetic isotope effects $(k_H/k_D>1.0)$ involving deuterated anilines suggest partial deprotonation by hydrogen bonding to the departing chloride ion.

• Bulletin of the Korean Chemical Society
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• v.17 no.3
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• pp.228-234
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• 1996

The rates of solvolysis of 1-(4-methoxyphenyl)-1-aryl-2,2,2-trifluoroethyl chlorides[I] in a variety of solvents were measured by an electroconductometric method. LArSR relationships (Yukawa-Tsuno eq.)were found to give a linear plot, log(k/ko)=-1.84[σo+0.918(σ+-σo)], in 80% aqueous ethanol. Small |ρ| and r values in comparison with 1-aryl-1-(trifluoromethyl)ethyl tosylate(ρ=-6.09, r=1.59) suggested that the carbocationic charge in the transition state was dispersed by a strong p-π donor, p-methoxy group. Linear mY plots with m 0.90 for all of the substituents in aqueous acetone and m=0.60-0.82 for those of aqueous ethanol indicate that this solvolysis proceeds via an SN1 mechanism with nucleophilic solvent assistance. Thiourea effects and isokinetic temperatures for the rate of solvolysis also can prove the above mechanism.

• Bulletin of the Korean Chemical Society
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• v.9 no.3
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• pp.157-160
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• 1988

The rates of hydrolysis of N-(benzenesulfonyl) benzimidoyl chlorides (p-H, $p-CH_3,\;p-CH_3,\;p-NO_2\;and m-NO_2$) have been measured by UV spectrometry in 60% methanol-water at $25^{\circ}C$ and a rate equation which can be applied over wide pH range was obtained. Below pH 7.00, the substituent effect on the hydrolysis rate of N-(benzenesulfonyl) benzimidoyl chloride was found to conform to the Hammett ${\sigma}$ constant with ${\rho}$ = -0.91, whereas above pH 9.00, with ${\rho}$ = 0.94. On the basis of the rate equation obtained and the effect of solvent, substituents and salt, the following reaction mechanism were proposed; below pH 7.00, the hydrolysis of N-(benzenesulfonyl) benzimidoyl chloride proceeds by $S_N1$ mechanism, however, above pH 9.00, the hydrolysis is initiated by the attack of the hydroxide ion and in the range of pH 7.00-9.00, these two reactions occur competitively.